Microbiocides are commonly used to control the growth of microorganisms in various industrial products and processes, including cooling water, paper manufacturing, oil field flood water, consumer products and the like. While a number of microbiocides are currently available, none is completely effective in all situations, and may also have undesirable characteristics in terms of handling, toxicology, spectrum of activity, cost and the like.
Chemical compounds which contain a geminal halonitro moiety are known to be bactericidal and fungicidal as reported by W. R. Bowman and R. J. Stretton, "Antimicrobial Activity of a Series of Halo-Nitro Compounds," Antimicrobial Agents and Chemotherapy, 2: 504-505 (1972 , and N. G. Clark, B. Croshaw, B. E. Leggetter, and D. F. Spooner, "Synthesis and Antimicrobial Activity of Aliphatic Nitro Compounds," J. Med. Chem., 17: 977-981 (1974).
A wide variety of these geminal halonitro compounds has been synthesized and tested for antimicrobial activity. While none shows activity which is outstanding in comparison to the rest of the group, the most effective compound has generally been found to be 2-bromo-2-nitro-1,3-propanediol. This compound has been commercialized under the name "Bronopol", and has been widely used in various fields where an antimicrobial agent is needed.
As indicated above, one such field where antimicrobial agents are particularly useful is in the oil and gas industry. For example, in United Kingdom Patent Application GB 2 183 477 A which was published June 10, 1987, novel solid antibacterial compositions are described which are indicated to be suitable for use in oil or gas wells against sulfate-reducing bacteria. These compositions were indicated to be solid nitroalkanols with 2-bromo-2-nitropropane-1,3-diol being preferred.
It is known that corrosion can occur in pipelines from oil wells due to the production of acids associated with the growth of bacterial colonies, particularly colonies of sulfate reducing bacteria. These colonies can develop in water in the presence of oil and can infect the entire well system.
It is also indicated in this application that a similar problem can exist in the collection of natural gases. Droplets of water can form on the interior of the gas pipe where colonies of bacteria can grow and give rise to corrosive conditions.
Thus, in the recovery of natural gases and in oil wells which utilize flooding operations, it is customary to employ an antibacterial compound to prevent or at least mimimize corrosion. The reference further indicates that known compounds and methods using antibacterial compounds to inhibit bacterial growth are not entirely satisfactory. Any compounds used, must have a high degree of antibacterial activity against sulfate-reducing bacteria, such as, Desulfovibrio desulfuricans.
The novelty of the invention disclosed in this reference appears to reside in the utilization of the nitroalkanols as a solid carrier which will dissolve, disintegrate or disperse in water but not in oil. The nitroalkanols can rapidly pass through the oil layer in a well and locate in the denser water layer where the bacteria are located.
Although the United Kingdom reference acknowledges the absence in the literature of known compounds which are satisfactory as antibacterial agents for this particularly application, and proposes the nitroalkanols as overcoming the deficiency, none of the other compounds disclosed is indicated to possess unexpected properties, although bronopol is considered to be the preferred compound. Accordingly, it appears that the inventors have equated all of the members of the disclosed class as being substantially equivalent for the intended purpose.
Also in U.S. Pat. No. 3,024,192, which issued Mar. 6, 1962 to E. O. Bennett et al there is disclosed an improved method in a flooding program for the recovery of oil from oil bearing subterranean formations, which utilize a halonitroalkanol such as 2-bromo-2-nitro-1,3-propandiol, 2-chloro-2-nitro-1-butanol and the like.
Accordingly, one or more of the following objects will be achieved by the practice of the present invention. It is an object of this invention to provide a microbiocidal composition which is effective at relatively low concentrations of the active ingredient. Another object of this invention is to provide a microbiocidal composition which is effective rapidly and can be used in a wide variety of applications. A still further object of this invention is to provide a microbiocidal composition which contains as a major active ingredient, 2,2-dibromo-2-nitroethanol. Another object is to provide a method for killing or inhibiting the growth of organisms in industrial water cooling systems. It is also an object of this invention to provide a method for killing or inhibiting the growth of organisms in processes used in the production of pulp and paper. A still further object of this invention is to provide methods of using the novel compositions in the treatment of a wide variety of organisms. A further object is to provide a microbiocidal composition which is useful as a fuel preservative. Another object is to provide a method for killing or inhibiting the growth of sulfate-reducing bacteria which cause corrosion in the metal works of oil and gas collection systems. These and other objects will readily become apparent to those skilled in the art in the light of the teachings herein set forth.